Tack is the alignment of a sailing vessel with respect to the wind when moving upwind: that is, when the vessel's bow is pointed within 90 degrees of the wind. If the wind is from starboard, the vessel is on "starboard tack", and if from port, on "port tack".
However, a better rule to use is to look at what side of the boat the sail is on. If the sail is on the port side of the boat you are on starboard tack and vice versa. For example, in smaller boats you will often let your sail past 90 degrees on a downwind leg and reverse the flow on the sail. This is called running by the lee. In this case the wind is coming over the port side of the boat but you are still on starboard tack because the sail is on the port side. Therefore this method of determining your tack overrules the first method described.

__________________In the harsh marine environment, something is always in need of repair...

Just realized my rss humor might have been insensitive due to to your nationality... None intended... my GM was 100% Pole!

Not problem at all

By the way - Red Swastika Society was a great Chinese humanitarian organisation - no offense possible

And swastika itself (in different shape varieties) was broadly used in in folklore of Slavic countries. You can find it easily in many places in Poland, for example in engravings on old houses in the mountain regions.

Not my fault, not Your fault this mad Mr. H took it as his "brand sign"...

As far as the Racing Rules of Sailing are concerned, what tack you are on is determined by boom position, regardless of whether a boat is sailing by the lee or not. This is a well travelled topic that comes up a lot with respect to overtaking boats when sailing downwind.

As far as the Racing Rules of Sailing are concerned, what tack you are on is determined by boom position, regardless of whether a boat is sailing by the lee or not. This is a well travelled topic that comes up a lot with respect to overtaking boats when sailing downwind.